Efeito do envelhecimento e do treinamento de força sobre a atividade da MMP-2 no tecido ósseo de ratos

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Ceilândia, 2019.As metaloproteinases de matriz (MMPs) são en dopeptidases de potencial regulatório da matriz extracelular Durante o envelhecimento o osso sofre modificações tornando o frágil em contrapartida o treinamento de força (TF pode ser uma alternativa para reduzir tais efeitos do envelhecimento . Objetivo Verificar o efeito do envelhecimento e do treinamento de força na atividade da MMP 2 em vértebras e fêmures de ratos. Materiais e Métod os : 20 ratos Wistar Novergicus Albinos, de 3 e 20 meses foram divididos em quatro grupos: Jove m Sedentário (JS ), Velho Sedentário V S), Jove m Treinado (JT) e Velho Treinado (VT). Os animais dos grupos treinados realizaram protocolo de TF . A ativi dade da MMP 2 d as vért ebras e fêmures foi a valiada por zimo grafia. Resultados Com relação as v é rtebra s a MM P 2 p ró apresen tou maior ativida d e n o grupo VT quando comparado com os demais grupos (p =0,001 ). A inda nas vér tebras, a MMP 2 intermediária foi maior no grupo JT do que nos grupos VS (p =0,01 ) e VT (p 0, 01 )), e a MMP 2 ativa foi maior em JS quando comparado em VS (p =0,01 ) e V T (p =0,01 E m r e l a ção a o fêmur, não houve diferença significati va (p< entre os grupos . A ati vidade da MMP 2 foi maior nas vértebras do que nos fêmures (p =0,001 )). Concl usão: O envelhecimen to parece ser um re gulador negativo para a atividade da MMP 2 nas vértebras , n ã o ocorrendo o mesmo com os fêmures. O T F n ão foi capaz de au men tar a atividade da MMP 2 no s ossos ana lisa dos Aprovado pelo Comi tê de Ética em Pesquisa com Animais da Universidade Federal de São Carlos (processo nº: 0 56 /201 0The matrix metalloproteinases (MMPs) are endopeptidases with regulatory potential at the extracellular matrix. During aging bones undergoes modifications making it fragile, in contrast, strength training (ST) could be an alternative to reduce the effects of aging. Objective: To verify the effect of aging and strength training on MMP-2 activity in vertebrae and femurs of rats. Materials and Methods: Twenty Albino Wistar rats (Rattus Norvegicus), aged 3 and 20 months, were divided into four groups: Sedentary Youth (SY), Sedentary Older (SO), Young Trained (YT) and Old Trained (OT). The animals of the trained groups performed the TF protocol. The MMP-2 activity of the vertebrae and femurs was analyzed by zymography. Results: Regarding the vertebrae, MMP-2 pro presented greater activity in the OT group when compared with other groups (p=0,001). In the vertebrae, intermediate MMP-2 was higher in the YT group than in the SO (p=0,01) and OT (p=0,01) groups, and the active MMP-2 was higher in SY when compared in SO (p=0,01) and OT (p=0,01). Regarding the femur, there was no significant difference (p<0,05) between the groups. The activity of MMP-2 was higher in the vertebrae than in the femurs (p=0,001). Conclusion: Aging seems to be a negative regulator for MMP-2 activity in the vertebrae, not the same with femurs. ST was not able to increase MMP-2 activity in the analyzed bones. (Approved by the Animal Research Ethics Committee of the Federal University of São Carlos (case nº: 056/2010))

Calcaneal tendon plasticity following gastrocnemius muscle injury in rat

Cross-talk between skeletal muscle and tendon is important for tissue homeostasis. Whereas the skeletal muscle response to tendon injury has been well-studied, to the best of our knowledge the tendon response to skeletal muscle injury has been neglected. Thus, we investigated calcaneal tendon extracellular matrix (ECM) remodeling after gastrocnemius muscle injury using a rat model. Wistar rats were randomly divided into four groups: control group (C; animals that were not exposed to muscle injury) and harvested at different time points post gastrocnemius muscle injury (3, 14, and 28 days) for gene expression, morphological, and biomechanical analyses. At 3 days post injury, we observed mRNA-level dysregulation of signaling pathways associated with collagen I accompanied with disrupted biomechanical properties. At 14 days post injury, we found reduced collagen content histologically accompanied by invasion of blood vessels into the tendon proper and an abundance of peritendinous sheath cells. Finally, at 28 days post injury, there were signs of recovery at the gene expression level including upregulation of transcription factors related to ECM synthesis, remodeling, and repair. At this time point, tendons also presented with increased peritendinous sheath cells, decreased adipose cells, higher Young’s modulus, and lower strain to failure compared to the uninjured controls and all post injury time points. In summary, we demonstrate that the calcaneal tendon undergoes extensive ECM remodeling in response to gastrocnemius muscle injury leading to altered functional properties in a rat model. Tendon plasticity in response to skeletal muscle injury merits further investigation to understand its physiological relevance and potential clinical implications

Resistance training modulates the matrix mtalloproteinase-2 activity in different trabecular bones in aged rats

Background: Aging decreases osteogenic ability, inducing harmful effects on the bone extracellular matrix (ECM), while exercise training has been indicated as a tool to counteract bone disorders related to advancing age. The modulation of bone ECM is regulated by several types of matrix metalloproteinase (MMP); however, MMP-2 activity in different trabecular bones in response to resistance training (RT) has been neglected. Remodeling differs in different bones under the application of the same mechanical loading. Thus, we investigated the effects of 12 weeks of RT on MMP-2 activity in the lumbar vertebra (L6), tibia, and femur of young (3 months) and older rats (21 months). Methods: Twenty Wistar rats were divided into four groups (five animals per group): young sedentary or trained and older sedentary or trained. The 12-week RT consisted of climbing a 1.1-m vertical ladder three times per week with progressive weights secured to the animals’ tails. The animals were killed 48 h after the end of the experimental period. The MMP-2 activity was assessed by the zymography method. Results: The aging process induced lower MMP-2 activity in the lumbar vertebrae and tibia (p=0.01). RT upregulated pro, intermediate, and active MMP-2 activity in the tibia of young rats (p=0.001). RT also upregulated pro and active MMP-2 activity in the lumbar vertebrae and tibia with advancing age (p=0.01). There was no significant difference (p> 0.05) between groups for MMP-2 of the femur, regardless of age and RT. Conclusion: The aging process impairs MMP-2 activity, but RT is a potential therapeutic approach to minimize the deleterious effects of ECM degeneration in different aged bones. Distinct MMP-2 responses to exercise training may result in specific remodeling processes